Which of the following is a sign of termite infestation?

Wood that sounds hollow when tapped is a classic indicator of termite infestation. Termites feed on wood from the inside out, which can create hollow spaces within the timber. When an infested piece of wood is tapped, it produces a hollow sound due to the absence of solid material inside. This is a reliable sign that termites may be present, as they weaken the wood structure over time, ultimately compromising its integrity.

In contrast, increased bird activity, unusual insect bites on humans, and visible ants on the premises do not specifically indicate termite infestation. Bird activity may be influenced by many factors unrelated to termites, while insect bites may be due to other pests such as mosquitoes or fleas. Similarly, the presence of ants does not necessarily correlate with termites, as they are separate pests, and their presence could indicate a different type of infestation or simply natural behavior rather than the presence of termites. Therefore, the hollow sound of wood is the most direct and relevant sign of a termite problem.